The image-forming system of liquid crystal displays or the like requires polarizing elements to be placed on both sides of a liquid crystal cell, and generally polarizing films are bonded thereto. A pressure-sensitive adhesive is commonly used to bond such polarizing films to a liquid crystal cell. When such polarizing films are bonded to a liquid crystal cell, a pressure-sensitive adhesive is generally used to bond the materials together so that optical loss can be reduced. In such a case, the pressure-sensitive adhesive is provided in advance as a pressure-sensitive adhesive layer on one side of a polarizing film, and the resulting pressure-sensitive adhesive layer attached polarizing film is generally used because it has some advantages such as no need for a drying process to fix the polarizing film. A release film is generally provided to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer attached polarizing film.
During the manufacture of a liquid crystal display, the pressure-sensitive adhesive layer-attached polarizing film is bonded to a liquid crystal cell. In this process, static electricity is generated when the release film is peeled off from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-attached polarizing film. The static electricity generated in this manner may affect the orientation of the liquid crystal in the liquid crystal display to cause a failure. The static electricity may also cause display unevenness when the liquid crystal display operates. For example, the static generation can be suppressed when an antistatic layer is formed on the outer surface of the polarizing film, but its effect is not high, and there is a problem in which static generation cannot be fundamentally prevented. To suppress static generation in a fundamental position, therefore, the pressure-sensitive adhesive layer is required to have an antistatic function. Concerning means for providing an antistatic function to a pressure-sensitive adhesive layer, for example, it is proposed that an ionic compound should be added to a pressure-sensitive adhesive used to form a pressure-sensitive adhesive layer (Patent Documents 1 and 2). Patent Document 1 discloses that an ionic solid including an imidazolium cation and an inorganic anion is added to an acrylic pressure-sensitive adhesive for use on polarizing films. Patent Document 2 discloses that an organic molten salt, such as an onium salt, which is in a liquid state at room temperature and includes a quaternary nitrogen atom-containing cation of 6 to 50 carbon atoms and a fluorine atom-containing anion, is added to an acrylic pressure-sensitive adhesive for use on polarizing films. There is also proposed a method in which a conductive polymer such as polythiophene is used as a binder to form an antistatic layer between a polarizing film and a pressure-sensitive adhesive layer (Patent Document 3). The pressure-sensitive adhesive layer attached polarizing film bonded to an object also needs to be durable.